Effect of L. Plantarum Y279 and W. Cibaria Y113 on microorganism, lipid oxidation and fatty acid metabolites in Yu jiaosuan, A Chinese tradition fermented snack

Fatty acids are one of the main sources of flavour in fermented Yu jiaosuan (YJS) in southwest China. Bacilli (50.18 %) and Oxyphotobacteria (32.70 %) were the dominant class. Lactiplantibacillus (40.51 %) and Weissella (20.43 %) were the dominant species in the inoculated fermented group (HY). The peroxide value (ZY: 0.025 g/100 g, HY: 0.016 g/100 g) and lipoxygenase (LOX) (ZY: 5.7654 U/min·g, HY: 3.3856 U/min·g) in the HY group were significantly lower compared with the natural fermentation group (ZY), while acid lipase activity (ZY: 0.3184 U/h·g, HY: 0.7075 U/h·g) and neutral lipase activity (ZY: 12.65443 U/h·g, HY: 20.25142 U/h·g) were significantly higher than the control sample. Totally 40 differential fatty acid metabolites were screened. Arachidonic acid metabolism, unsaturated fatty acid biosynthesis and linoleic acid metabolism were potential metabolic pathways. Seven major bacterial species were closely associated with 15 differential fatty acid. This study contributes to the targeted production of fatty acid functional active substances of YJS.

Elucidation of the effects of autochthonous starter on nitrogen-containing compounds during fermentation of Yujiangsuan by metabolomics

To understand the role of microorganisms in nitrogen (N)-containing compound changes during the processing of Yujiangsuan by autochthonous starter cultures, the GC-TOF-MS-based metabolomics method was adopted to investigate the effects of Weissella cibaria and Lactobacillus plantarum. The results demonstrated that inoculation of autochthonous strains led to differential metabolites, such as fatty acids, organic oxygen compounds, and carboxylic acids on day 4 to day 12 of fermentation. The N-containing compounds under the inoculated fermentation group showed a faster relative concentration change. Nucleotide metabolism and arginine and proline metabolism exerted an influence on the formation of N-containing compounds. Apart from that, the effect of W. cibaria and L. plantarum on the hydrolysis of macromolecules was the main factor causing differences in major N-containing compounds.

Effects of a Novel Starter Culture on Quality Improvement and Putrescine, Cadaverine, and Histamine Inhibition of Fermented Shrimp Paste

Fermented shrimp paste is a popular food in Asian countries. However, biogenic amines (BAs) are a typically associated hazard commonly found during the fermentation of shrimp paste and pose a food-safety danger. In this work, an autochthonic salt-tolerant Tetragenococcus muriaticus TS (T. muriaticus TS) strain was used as a starter culture for grasshopper sub shrimp paste fermentation. It was found that with the starter culture, putrescine, cadaverine, and histamine concentrations were significantly lower (p < 0.05) with a maximal reduction of 19.20%, 14.01%, and 28.62%, respectively. According to high-throughput sequencing data, T. muriaticus TS could change the interactions between species and reduce the abundance of bacterial genera positively associated with BAs, therefore inhibiting the BA accumulation during shrimp paste fermentation. Moreover, the volatile compounds during the fermentation process were also assessed by HS-SPME-GC-MS. With the starter added, the content of pyrazines increased, while the off-odor amines decreased. The odor of the shrimp paste was successfully improved. These results indicate that T. muriaticus TS can be used as an appropriate starter culture for improving the safety and quality of grasshopper sub shrimp paste.